Quaternary ammonium bromide functionalized polyethylene glycol: A highly efficient and recyclable catalyst for selective synthesis of 5-aryl-2-oxazolidinones from carbon dioxide and aziridines under solvent-free conditions

A quaternary ammonium bromide covalently bound to polyethylene glycol (PEG, MW = 6000), i.e., PEG(6000)-(NBu3Br)(2), was found to be an efficient and recyclable catalyst for the cycloaddition reaction of aziridines to CO2 under mild conditions without utilization of additional organic solvents or cocatalysts. As a result, 5-aryl-2-oxazolidinone was obtained in high yield with excellent regioselectivity. The catalyst worked well for a wide variety of 1-alkyl-2-arylaziridines. Besides, the catalyst could be recovered by centrifugation and reused without significant loss of catalytic activity and selectivity.